I would generally agree that dd is not a great benchmarking tool, but you could use multiple instances to multiple files, and larger block sizes are more efficient. And it's always good to check iostat and mpstat for io and cpu bottlenecks. Also note that an initial run that creates files may be quicker because it just allocates blocks, whereas subsequent rewrites require copy-on-write.
----- Reply message ----- From: "Peter Tribble" <peter.trib...@gmail.com> To: "Gregory Durham" <gregory.dur...@gmail.com> Cc: <zfs-discuss@opensolaris.org> Subject: [zfs-discuss] Issues with supermicro Date: Wed, Aug 10, 2011 10:56 On Wed, Aug 10, 2011 at 1:45 AM, Gregory Durham <gregory.dur...@gmail.com> wrote: > Hello, > We just purchased two of the sc847e26-rjbod1 units to be used in a > storage environment running Solaris 11 express. > > We are using Hitachi HUA723020ALA640 6 gb/s drives with an LSI SAS > 9200-8e hba. We are not using failover/redundancy. Meaning that one > port of the hba goes to the primary front backplane interface, and the > other goes to the primary rear backplane interface. > > For testing, we have done the following: > Installed 12 disks in the front, 0 in the back. > Created a stripe of different numbers of disks. After each test, I > destroy the underlying storage volume and create a new one. As you can > see by the results, adding more disks, makes no difference to the > performance. This should make a large difference from 4 disks to 8 > disks, however no difference is shown. > > Any help would be greatly appreciated! > > This is the result: > > root@cm-srfe03:/home/gdurham~# time dd if=/dev/zero > of=/fooPool0/86gb.tst bs=4096 count=20971520 > ^C3503681+0 records in > 3503681+0 records out > 14351077376 bytes (14 GB) copied, 39.3747 s, 364 MB/s So, the problem here is that you're not testing the storage at all. You're basically measuring dd. To get meaningful results, you need to do two things: First, run it for long enough so you eliminate any write cache effects. Writes go to memory and only get sent to disk in the background. Second, use a proper benchmark suite, and one that isn't itself a bottleneck. Something like vdbench, although there are others. -- -Peter Tribble http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
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